Zimbra Backup (still running?)

In an attempt to troubleshoot backups which have not executed properly for a while, I ran the following:

/opt/zimbra/bin/zmbackup -f -a all

...and receive the following error:

Error occurred: invalid request: incremental backup is still in progress

Looking into this further, after running 'zmbackupquery', all backups listed have completed successfully. I looked into the mailbox.log, and only found a stack trace with the same resulting error 'Incremental backup still in progress'.

Has anyone else had this issue, is there something I'm missing here to find an existing or uncompleted backup?

We just recently saw this after we had a backup not complete due the volume filling in the middle of the backup. We were able to correct the issue by restarting zimbra (zmcontrol stop;zmcontrol start). We also deleted everything that was in /tmp/, which is where the backup is staged before moving it over to